全文获取类型
收费全文 | 7651篇 |
免费 | 534篇 |
国内免费 | 2篇 |
出版年
2023年 | 35篇 |
2022年 | 57篇 |
2021年 | 137篇 |
2020年 | 80篇 |
2019年 | 114篇 |
2018年 | 139篇 |
2017年 | 134篇 |
2016年 | 233篇 |
2015年 | 381篇 |
2014年 | 433篇 |
2013年 | 484篇 |
2012年 | 717篇 |
2011年 | 686篇 |
2010年 | 437篇 |
2009年 | 404篇 |
2008年 | 564篇 |
2007年 | 468篇 |
2006年 | 452篇 |
2005年 | 362篇 |
2004年 | 388篇 |
2003年 | 364篇 |
2002年 | 340篇 |
2001年 | 49篇 |
2000年 | 42篇 |
1999年 | 59篇 |
1998年 | 73篇 |
1997年 | 55篇 |
1996年 | 56篇 |
1995年 | 39篇 |
1994年 | 34篇 |
1993年 | 46篇 |
1992年 | 26篇 |
1991年 | 21篇 |
1990年 | 14篇 |
1989年 | 24篇 |
1988年 | 14篇 |
1987年 | 17篇 |
1986年 | 17篇 |
1985年 | 13篇 |
1984年 | 17篇 |
1983年 | 27篇 |
1982年 | 15篇 |
1981年 | 16篇 |
1980年 | 12篇 |
1978年 | 7篇 |
1977年 | 11篇 |
1976年 | 10篇 |
1975年 | 6篇 |
1974年 | 7篇 |
1971年 | 5篇 |
排序方式: 共有8187条查询结果,搜索用时 62 毫秒
151.
John R. Pruett Jr Sarah Hoertel John N. Constantino Angela LaMacchia Moll Kelly McVey Emma Squire Eric Feczko Daniel J. Povinelli Steven E. Petersen 《PloS one》2013,8(3)
To explore mechanisms underlying reduced fixation of eyes in autism, children with Autistic Spectrum Disorders (ASD) and typically developing children were tested in five visual search experiments: simple color feature; color-shape conjunction; face in non-face objects; mouth region; and eye region. No group differences were found for reaction time profile shapes in any of the five experiments, suggesting intact basic search mechanics in children with ASD. Contrary to early reports in the literature, but consistent with other more recent findings, we observed no superiority for conjunction search in children with ASD. Importantly, children with ASD did show reduced accuracy for eye region search (p = .005), suggesting that eyes contribute less to high-level face representations in ASD or that there is an eye region-specific disruption to attentional processes engaged by search in ASD. 相似文献
152.
Anthony C. Fries Jacqueline M. Nolting Angela Danner Robert G. Webster Andrew S. Bowman Scott Krauss Richard D. Slemons 《PloS one》2013,8(3)
Three H14 influenza A virus (IAV) isolates recovered in 2010 during routine virus surveillance along the Mississippi Migratory Bird Flyway in Wisconsin, U.S.A. raised questions about the natural history of these rare viruses. These were the first H14 IAV isolates recovered in the Western Hemisphere and the only H14 IAV isolates recovered since the original four isolates in 1982 in Asia. Full length genomic sequencing of the 2010 H14 isolates demonstrated the hemagglutinin (HA) gene from the 1982 and 2010 H14 isolates showed 89.6% nucleotide and 95.6% amino acid similarity and phylogenetic analysis of these viruses placed them with strong support within the H14 subtype lineage. The level of genomic divergence observed between the 1982 and 2010 viruses provides evidence that the H14 HA segment was circulating undetected in hosts and was not maintained in environmental stasis. Further, the evolutionary relationship observed between 1982 H14 and the closely related H4 subtype HA segments were similar to contemporary comparisons suggesting limited adaptive divergence between these sister subtypes. The nonstructural (NS) segment of one 2010 isolate was placed in a NS clade isolated infrequently over the last several decades that includes the NS segment from a previously reported 1982 H14 isolate indicating the existence of an unidentified pool of genomic diversity. An additional neuraminidase reassortment event indicated a recent inter-hemispheric gene flow from Asia into the center of North America. These results demonstrate temporal and spatial gaps in the understanding of IAV natural history. Additionally, the reassortment history of these viruses raises concern for the inter-continental spread of IAVs and the efficacy of current IAV surveillance efforts in detecting genomic diversity of viruses circulating in wild birds. 相似文献
153.
154.
Annalisa Lattanzi Bernhard Gentner Daniela Corno Tiziano Di Tomaso Pieter Mestdagh Frank Speleman Luigi Naldini Angela Gritti 《PloS one》2013,8(6)
Several microRNAs (miRNAs) that are either specifically enriched or highly expressed in neurons and glia have been described, but the identification of miRNAs modulating neural stem cell (NSC) biology remains elusive. In this study, we exploited high throughput miRNA expression profiling to identify candidate miRNAs enriched in NSC/early progenitors derived from the murine subventricular zone (SVZ). Then, we used lentiviral miRNA sensor vectors (LV.miRT) to monitor the activity of shortlisted miRNAs with cellular and temporal resolution during NSC differentiation, taking advantage of in vitro and in vivo models that recapitulate physiological neurogenesis and gliogenesis and using known neuronal- and glial-specific miRNAs as reference. The LV.miRT platform allowed us monitoring endogenous miRNA activity in low represented cell populations within a bulk culture or within the complexity of CNS tissue, with high sensitivity and specificity. In this way we validated and extended previous results on the neuronal-specific miR-124 and the astroglial-specific miR-23a. Importantly, we describe for the first time a cell type- and differentiation stage-specific modulation of miR-93 and miR-125b in SVZ-derived NSC cultures and in the SVZ neurogenic niche in vivo, suggesting key roles of these miRNAs in regulating NSC function. 相似文献
155.
156.
Maria Adelaide Marini Simona Frontoni Elena Succurro Franco Arturi Teresa Vanessa Fiorentino Angela Sciacqua Marta Letizia Hribal Francesco Perticone Giorgio Sesti 《PloS one》2013,8(10)
Reduced insulin clearance has been shown to predict the development of type 2 diabetes. Recently, it has been suggested that plasma glucose concentrations ≥8.6 mmol/l (155 mg/dl) at 1 h during an oral glucose tolerance test (OGTT) can identify individuals at high risk for type 2 diabetes among those who have normal glucose tolerance (NGT 1 h-high). The aim of this study was to examine whether NGT 1 h-high have a decrease in insulin clearance, as compared with NGT individuals with 1-h post-load glucose <8.6 mmol/l (l (155 mg/dl, NGT 1 h-low). To this end, 438 non-diabetic White individuals were subjected to OGTT and euglycemic-hyperinsulinemic clamp to evaluate insulin clearance and insulin sensitivity. As compared with NGT 1 h-low individuals, NGT 1 h-high had significantly higher 1-h and 2-h post-load plasma glucose and 2-h insulin levels as well as higher fasting glucose and insulin levels. NGT 1 h-high exhibited also a significant decrease in both insulin sensitivity (P<0.0001) and insulin clearance (P = 0.006) after adjusting for age, gender, adiposity measures, and insulin sensitivity. The differences in insulin clearance remained significant after adjustment for fasting glucose (P = 0.02) in addition to gender, age, and BMI. In univariate analyses adjusted for gender and age, insulin clearance was inversely correlated with body weight, body mass index, waist, fat mass, 1-h and 2-h post-load glucose levels, fasting, 1-h and 2-h post-load insulin levels, and insulin-stimulated glucose disposal. In conclusion, our data show that NGT 1 h-high have a reduction in insulin clearance as compared with NGT 1 h-low individuals; this suggests that impaired insulin clearance may contribute to sustained fasting and post-meal hyperinsulinemia. 相似文献
157.
Angela L. McDowell Ashlee B. Filippone Alex Balbir Anne Germain Christopher P. O’Donnell 《PloS one》2013,8(6)
Introduction
Studies suggest that sleep plays a role in traumatic memories and that treatment of sleep disorders may help alleviate symptoms of posttraumatic stress disorder. Fear-conditioning paradigms in rodents are used to investigate causal mechanisms of fear acquisition and the relationship between sleep and posttraumatic behaviors. We developed a novel conditioning stimulus (CS) that evoked fear and was subsequently used to study re-exposure to the CS during sleep.Methods
Experiment 1 assessed physiological responses to a conditioned stimulus (mild transient hypercapnia, mtHC; 3.0% CO2; n = 17)+footshock for the purpose of establishing a novel CS in male FVB/J mice. Responses to the novel CS were compared to tone+footshock (n = 18) and control groups of tone alone (n = 17) and mild transient hypercapnia alone (n = 10). A second proof of principle experiment re-exposed animals during sleep to mild transient hypercapnia or air (control) to study sleep processes related to the CS.Results
Footshock elicited a response of acute tachycardia (30–40 bpm) and increased plasma epinephrine. When tone predicted footshock it elicited mild hypertension (1–2 mmHg) and a three-fold increase in plasma epinephrine. When mtHC predicted footshock it also induced mild hypertension, but additionally elicited a conditioned bradycardia and a smaller increase in plasma epinephrine. The overall mean 24 hour sleep–wake profile was unaffected immediately after fear conditioning.Discussion
Our study demonstrates the efficacy of mtHC as a conditioning stimulus that is perceptible but innocuous (relative to tone) and applicable during sleep. This novel model will allow future studies to explore sleep-dependent mechanisms underlying maladaptive fear responses, as well as elucidate the moderators of the relationship between fear responses and sleep. 相似文献158.
Alastair J. King Marc R. Arnone Maureen R. Bleam Katherine G. Moss Jingsong Yang Kelly E. Fedorowicz Kimberly N. Smitheman Joseph A. Erhardt Angela Hughes-Earle Laurie S. Kane-Carson Robert H. Sinnamon Hongwei Qi Tara R. Rheault David E. Uehling Sylvie G. Laquerre 《PloS one》2013,8(7)
Mitogen-Activated Protein Kinase (MAPK) pathway activation has been implicated in many types of human cancer. BRAF mutations that constitutively activate MAPK signalling and bypass the need for upstream stimuli occur with high prevalence in melanoma, colorectal carcinoma, ovarian cancer, papillary thyroid carcinoma, and cholangiocarcinoma. In this report we characterize the novel, potent, and selective BRAF inhibitor, dabrafenib (GSK2118436). Cellular inhibition of BRAFV600E kinase activity by dabrafenib resulted in decreased MEK and ERK phosphorylation and inhibition of cell proliferation through an initial G1 cell cycle arrest, followed by cell death. In a BRAFV600E-containing xenograft model of human melanoma, orally administered dabrafenib inhibited ERK activation, downregulated Ki67, and upregulated p27, leading to tumor growth inhibition. However, as reported for other BRAF inhibitors, dabrafenib also induced MAPK pathway activation in wild-type BRAF cells through CRAF (RAF1) signalling, potentially explaining the squamous cell carcinomas and keratoacanthomas arising in patients treated with BRAF inhibitors. In addressing this issue, we showed that concomitant administration of BRAF and MEK inhibitors abrogated paradoxical BRAF inhibitor-induced MAPK signalling in cells, reduced the occurrence of skin lesions in rats, and enhanced the inhibition of human tumor xenograft growth in mouse models. Taken together, our findings offer preclinical proof of concept for dabrafenib as a specific and highly efficacious BRAF inhibitor and provide evidence for its potential clinical benefits when used in combination with a MEK inhibitor. 相似文献
159.
160.